login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A161077 Number of partitions of n into primes or 1 where every part appears at least 2 times. 1
0, 1, 1, 2, 1, 4, 2, 5, 5, 8, 6, 12, 10, 16, 16, 22, 21, 31, 30, 40, 42, 53, 55, 71, 73, 90, 96, 116, 123, 149, 157, 186, 200, 234, 250, 292, 312, 360, 388, 443, 476, 543, 584, 660, 712, 800, 862, 967, 1041, 1160, 1252, 1390, 1497, 1659, 1786, 1970, 2124, 2336, 2513, 2760 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..1000

FORMULA

G.f.: -1+(1+x^2/(1-x))*product[1+x^{2*p(j)}/(1-x^{p(j)}, j=1..infinity], where p(j) is the j-th prime. - Emeric Deutsch, Jun 27 2009

EXAMPLE

a(8)=5 because we have 3311, 2222, 22211, 221111, and 1^8. - Emeric Deutsch, Jun 27 2009

MAPLE

g := -1+(1+x^2/(1-x))*(product(1+x^(2*ithprime(j))/(1-x^ithprime(j)), j = 1 .. 20)): gser := series(g, x = 0, 70): seq(coeff(gser, x, n), n = 1 .. 60); # Emeric Deutsch, Jun 27 2009

CROSSREFS

Sequence in context: A161307 A161241 A161026 * A161293 A328163 A217916

Adjacent sequences:  A161074 A161075 A161076 * A161078 A161079 A161080

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jun 02 2009

EXTENSIONS

Definition edited to "primes or 1" by R. H. Hardin, Jun 22 2009

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 14 23:58 EDT 2019. Contains 328025 sequences. (Running on oeis4.)